Pituitary adenomas removed during surgery will be evaluated for immunoreactive growth hormone and prolactin content, for correlation of clinical and histophysiological data, at the light- and electron-microscopic level. Cyclic AMP-dependent protein kinases from normal and goitrous rat thyroids will be purified and compared with respect to their response to Ca ions, Mg ions and allosteric modifiers. Cyclic nucleotide (cAMP, cGMP) phosphodiesterases from such thyroids will also be compared as to the kinetics Vmax, apparent Km) of their action on the substrates. The added iodide formed in the thyroid under the effect of TSH will be studied with respect to its response to perchlorate and propylthiouracil, in an attempt to evaluate the fit of a 2-compartment vs. 1-compartment model to transported and intraglandularly-produced thyroid iodide.